Programmable remote control of electrical devices, such as lights, through a main module is known. The commercially available X-10 residential device control system is an example of this. Systems such as these are used mainly in home control applications, performing tasks such as controlling lights, TVs, stereos etc, using a remote control or a programmable schedule. At a site, electrical devices are plugged into control modules which are plugged into the household sockets. A main module is also plugged into a socket at the site. The main module allows programmed control of the devices connected to each control module. To accomplish this, the main module communicates with control modules and devices are activated and deactivated according to a particular scheduled program for each control module. Typically, the user has extensive control over activation schedules for the devices, which makes the system harder to use and increases the chances of programming error.
Further, the programming flexibility of the above device is limited. The scheduled program must be changed as the activation or deactivation times change. In particular, if a porch light is programmed to be activated at a certain time each night, as the sunset time changes for that location, the activation time becomes either too early or too late. Other modifications such as using light sensors to automatically adjust the activation times are costly and the sensors may malfunction through sensor-blocking dirt or breakage.
Systems exist for adjusting activation and deactivation of devices according to specific sunrise and sunset times. See U.S. Pat. Nos. 4,857,759 and 5,254,908. Such systems are limited in their flexibility as they simply activate and deactivate devices and provide no other functionality.